How to use Boric Acid properly?

My boyfriend and I have been having a roach problem in our apartment for awhile (btw if you're planing on moving to North Dallas DO NOT lease at Preston Oaks apartments,the one we're currently in right now.) At the suggestion of my mom and other family members we put some boric acid down around the base boards,under the sinks,etc. With that being said (and I hope this makes some sense) are you suppose to leave the powder exposed (right now it looks like a crack addicts paradise in here...and no I do not advocate the use of drugs)? Or are you suppose to blend in the powder into your carpet,sweep/blow it under the refrigerator/stove,etc to make it less expose and so that the chances of ingesting it or getting it on you are less likely?