I payed for some school supplies but I don’t have a tax form for it what do I do?

If you're an eligible educator, you can deduct up to $250 ($500 if married filing jointly and both spouses are eligible educators, but not more than $250 each) of unreimbursed trade or business expenses. Qualified expenses are amounts you paid or incurred for participation in professional development courses, books, supplies, computer equipment (including related software and services), other equipment, and supplementary materials that you use in the classroom. For courses in health or physical education, the expenses for supplies must be for athletic supplies. 

You're an eligible educator if, for the tax year you're a kindergarten through grade 12 teacher, instructor, counselor, principal or aide for at least 900 hours a school year in a school that provides elementary or secondary education as determined under state law.

Go to Federal>Deductions and Credits>Employment Expenses>Teacher (Educator) Expenses