Learn simple Urdu postpositions. Some of the most commonly used postpositions are maiⁿ (in), par (on), se (from), ko (to), and tak (up to). Practice making simple phrases and sentences with these postpositions. "In America" would be "Amrika maiⁿ." "On the table" would be "mez par." "From the store" would be "dukan se." Practice the phrases until you are comfortable with the word order.
Learn the oblique case of pronouns. When nouns and pronouns are followed by postpositions, they often change their spelling and the way they are pronounced. For example, the first person pronoun "mai" changes to "mujh" in the oblique case. If you need to say the phrase "from me," you will say "mujh se," not "mai se."
Learn the oblique case of common nouns. Remembering to use the oblique case with nouns can be difficult for nonnative speakers to get used to. Nouns ending in "alif" usually change the ending from the [a] sound to the [e] sound. The word "larka," "boy," becomes "larke" in the oblique case. To say "from the boy," you would say "larke se."
Start learning compound postpositions that are made up of more than one word. Many of these compound postpositions start with "ke" or "se." Useful expressions include "ke sath" (with), "ke nicche" (under), "ke picche" (behind), "ke ba9d" (after), and "se pahle" (before). To say the phrase "with you" in the polite or formal way, you would say "Aap ke sath."
Learn the oblique of infinitive verbs, and learn how to use infinitive verbs with postpositions. Take the infinitive verb "jana" meaning "to go." In the oblique case it becomes "jane." To say the phrase "before going," you would say "jane se pahle."
Practice all of the postpositional phrases by talking to a native speaker. Ask him or her to correct you, especially on word order and using the oblique case. The more you practice and speak Urdu, the more using postpositions will feel natural to you.