Since you indicated you don't know much about carburetors, something that may interest you is filters will normally take out dirt that gets pumped up from the gas tank, as others have mentioned. However that is not normally the cause of a problem. The normal cause is old gas that has turned to varnish by being allowed to sit for some time. The volatile part of the gas evaporates leaving the varnish behind, and that gums up the little holes, called "jets", that allow gas to flow to the engine.
Another cause is water left over from the alcohol that is now added to gasoline to meet emission standards. Stuff grows in the water and that can block the jets. Also, water won't go thru the jets unless it is mixed with alcohol.
So, change the filter. It probably looks like a very short cigar and is right at where the fuel line connects to the carburetor. (It may be on the top right on the Holly if I remember correctly.)
I don't think your Holly has a drain plug at the bottom unless it is very old, but if it does, you could drain out the debris and water. Taking the top off of the carburetor is a job better left to someone familiar with rebuilding a carburetor, so removing and exchanging it with a rebuilt would be the better choice. Good luck.
