You can cut 100 discs from watmann filter paper and rinse them in one ml containing solution of certain antibiotic you chosed.Then you dry the wet discs aseptically at 37 C,now they ready for antibiotic disc method of sensitivity.
Mohemid has explained it very simply. I would like to add something. Use sterilized Whatmann filter paper for this process. You can sterilize it by keeping in petriplate while autoclaving. I have used this method http://globalresearchonline.net/journalcontents/v23-1/51.pdf
You can also get ready made standard antibiotic discs in different concentrations from the suppliers.