Use the recommended concentration 2.5ug Fc blocking for 50-100uL staining solution. The staining solution being the solution you use with your antibody staining, just without the antibody. You incubate the Fc block for 10-20 min, then you remove the solution and can add your antibody solution with Ab right onto your sample. If you need more volume just do the math (so 1mL of Fc blocking=25-50 ug Fc Blocking + 1 mL stain solution) 

Hi Daniel, thanks for the answer. However the question i have is, the FC block comes as a liquid, so how do i take 2.5ug of that? it doesn't make sense to me.

Thanks

It states at the top of the spec sheet. 50ug at 0.5mg/mL. Aka, equal to 0.5ug/uL. So for every 1 uL of stock you use you will get 0.5ug of Fc block. So you need 5uL of stock fc blocker for every 100 uL of staining solution (without antibody).  Does that help?