The difficulty with a fission bomb is getting enough uranium or plutonium or other fissile material together for the bomb yield you want (at least above the critical mass for your chosen material), and refining it to fissile form, (since most fissile material found in nature is a more stable variety), and then separating the fissile bits with something thin but neutron absorptive.

The rest is just slamming the material together with a small explosive so that it passes the critical mass state and starts a chain reaction.

This is information you can find in many places if you're willing to put the effort in to go searching for it. Knowing this knowledge does not get you any closer to making atomic bombs. The process of mining uranium or plutonium is difficult, expensive, and very likely to get you caught before you even make it to the enrichment step of the process thanks to constant world-wide spy satellite surveillance.

Unless you are a nation, your only chance of making a nuclear bomb would be to find a lost nuclear submarine and convert the nuclear material inside of it before you were caught.