Pics would help but it sounds like you have an Optic Ready Carbine, basic round handguards, flat top receiver and gas block.
The issue with trying to get your gas block rail to line up with a metal handguard rail is brand and tolerance. It would be hard to find a perfect, gapless match.
Replacing the current gas block is fairly straight forward if you know what your doing, which from your post, and I'm not trying to be an arse, you don't, which means a trip to a smith.
If you go with a low profile gas block you open yourself to unlimited possibilities. You can go with a replacement metal rail that would reach all the way to the muzzle if you want.
If you keep the current black and just want to go with handguards the simpliest would be Magpul OEM handguards. Or possible metal drop in quad rails.
MOE(R) M-LOK(R) Hand Guard, Carbine-Length – AR15/M4
AR-15 Quad Rail Handguard - Carbine | Drop-In
Again just be aware the quad rail may need to modified at the front to clear your current rail.