I recently installed a new water heater in my house. Everything went fine with installation but now the water isn't getting hot. The cold comes out fine. On the hot side it will flow fine for a sec then barely comes out at all and is not getting hot at all. Now what's going on and I can't really afford a plumber. Can someone help?

You may have installed heat trap nipples see the image below.

There can be a situation where the heat traps prevent the water from circulating or Crud has clogged up a valve, Thanks.

John

Suggest you connect a hose to the water heater drain valve. Open the drain valve and see if you have water coming out under force and if it is hot.
If you have hot water under force, the problem is on the hot water output side of the heater. As John pointed out, if you have heat trap nipples the may be installed incorrectly.

If you do not have hot water coming out under force the problem is on the cold water input side. Check to insure that the cold water stop valve is open. Also check to insure that the cold water heat trap nipple is installed correctly.