Student visa process is explained at https://www.ustraveldocs.com/pk/pk-niv-typefandm.asp
US Student visa is called F1 visa and must be applied online using below forms and information
Form DS 160 – https://ceac.state.gov/genniv/
SEVIS Fee – https://www.fmjfee.com/i901fee/index.html
In addition to these items, you must present an interview appointment letter confirming that you booked an appointment through this service. You may also bring whatever supporting documents you believe support the information provided to the consular officer.
Step 1 Complete the Nonimmigrant Visa Electronic Application (DS-160) form.
Step 2 Pay the visa application fee.
Step 3 Schedule your appointment on this web page. You will need the following information in order to schedule your appointment:
Step 4 Visit the U.S. Embassy or Consulate on the date and time of your visa interview. You must bring a printed copy of your appointment letter, your DS-160 confirmation page, one photograph taken within the last six months, your current and all old passports, and the original visa fee payment receipt. Applications without all of these items will not be accepted.
Supporting documents are only one of many factors a consular officer will consider in your interview. Consular officers look at each application individually and consider professional, social, cultural and other factors during adjudication. Consular officers may look at your specific intentions, family situation, and your long-range plans and prospects within your country of residence. Each case is examined individually and is accorded every consideration under the law.
Do not present false documents. Fraud or misrepresentation can result in permanent visa ineligibility. If confidentiality is a concern, please know that the U.S. Embassy or Consulate will not make your true information available to anyone and will respect the confidentiality of your information.
You should bring the following documents to your interview:
Spouses and/or unmarried children under the age of 21 who wish to accompany or join the principal visa holder in the United States for the duration of his or her stay require derivative F or M visas. There is no derivative visa for the parents of F or M holders.
Family members who do not intend to reside in the United States with the principal visa holder, but wish to visit for vacations only, may be eligible to apply for visitor (B-2) visas.
Spouses and dependents may not work in the United States on a derivative F or M visa. If your spouse/child seeks employment, the spouse must obtain the appropriate work visa.
Supporting Documents for Dependents
Applicants with dependents must also provide:
F-1 visa holders may be eligible for up to 12 months of optional practical training following completion of all course requirements for graduation (not including thesis or equivalent), or after completion of all requirements. OPT is separate from a student’s academic work, and time for OPT will not normally be reflected during the student’s academic program or in the completed study date. Students applying for an F visa to do OPT may present an I-20 with an original end of study date that may have passed. However, these I-20s must be annotated by the designated school official to reflect approval of an OPT program that extends beyond the end of the regular period of study. In addition, the student must have proof that USCIS has approved their practical training program or that an application is pending, either in the form of an approved Employment Authorization Card or a Form I-797 indicating that s/he has a pending application for an OPT program.
Students who are away from classes for more than five months can expect to apply for and receive a new F-1 or M-1 student visa to return to school following travel abroad, as explained below.
A student (F-1 or M-1) may lose that status if they do not resume studies within five months of the date of transferring schools or programs, under immigration law. If a student loses status, unless USCIS reinstates the student’s status, the student’s F or M visa would also be invalid for future travel returning to the United States. For more information see the USCIS website, and instructions for Application for Extend/Change of Nonimmigrant Status Form I-539 to request reinstatement of status.
Students who leave the United States for a break in studies of five months or more may lose their F-1 or M-1 status unless their activities overseas are related to their course of study. In advance of travel, students may want to check with their designated school official, if there is a question about whether their activity is related to their course of study.
When the Customs and Border Protection (CBP) immigration inspector at port of entry is presented a previously used, unexpired F-1 or M-1 visa by a returning student who has been outside the United States and out of student status for more than five months, a CBP immigration inspector may find the student inadmissible for not possessing a valid nonimmigrant visa. CBP may also cancel the visa after granting the student permission to withdraw the application for admission. Therefore, it is prudent for students to apply for new visas at a U.S. Embassy or Consulate abroad prior to traveling to the United States to return to their studies, after an absence of more than five months that is not related to their course of study.