It is imperative that you have a copy of your transcript from the college. Even if it has been several years since you have been in school the transcript needs to include information such as the course name, course number, when it was taken and your final grade. This information will be used by the university to determine if those credits are valid. If a long time has lapsed since you were in school, or you got a poor grade, the university may decline to accept the credit.
Many universities offer websites where students can evaluate how many credits will transfer before they even submit an application. This can give you an idea as to which credits will count toward your final degree and which credits will not. This website tool is especially popular within state university systems. Because they are integrated, students can easily find out the credits that will transfer. Generally the database asks the student to input the name of the college he attended, course name or number, date he took the class and the final grade. Based on these parameters the database may or may not accept the credit.
Even if you filled out a preliminary form online and were told what credits will transfer, ultimately you will need to contact the office of admissions for an application. Many universities allow potential students to fill out their application online. There will be a section of the application that asks if you wish to transfer credit. Fill in the information from your transcript and submit the application along with the fee and other required documentation, which may vary by major and university.
After submitting the application, you will first find out if you have been accepted to the university. If you have, the welcome packet will detail what courses successfully transferred toward your major and which courses did not. Some universities might choose to give partial credit of classes. Depending on your major, this may add more time to your collegiate experience at the university. At that point you must weigh if transferring these credits to ultimately receive a degree from the new university is worth the extra time and cost versus staying at your current college and completing a degree there.