USCIS require applicants to submit applicable fee along with the forms for desired service. Depending on the service you are applying for there is a specific form and a specified fee for it.
How to submit the forms and fee?
most of the forms and services are not available online at USCIS.
See more information about e-filing here at USCIS E filing service.
How to pay USCIS fees?
For all forms being submitted online fee can be paid online long with the fom with a credit card or directly through your checking or savings account.
For all paper based application, a check or monitored can be submitted , made payable to USCIS.
Fee for Biometrics
Certain immigration services may require Fingerprinting and Biometrics to be performed and completed , and a separate fee of $85 for bio metrics must be paid in addition to the service fee for Bio-metrics.
See complete details of various USCIS forms and associated services fee.
USCIS Fee Waiver Guidance
If a applicant is unable to make the fee payment due to eligible situations fee can be waived.
See complete details about USCIS fee waiver guidelines.