Lets' start with the basics. Pull the fuel line off the carb, and let it run into a suitable container. Is it running? Good. If it's not, find out why.
Then, remove the float bowl. Assuming your carb is built like most, right up the middle of where you just pulled the bowl bolt out, is your main jet. Remove it (usually with a small, flat screwdriver. Examine it. There's a hole up the middle of it. Poke a fine wire (like a bag tie with the paper removed) through it a few times, ensuring it is completely clean. Put it all back together, and try it. If that didn't rectify things, you'll have to go deeper.
Meantime, please post the model number of your engine, and we'll see what we can dig up for info.