Lets start with the different components you'll need to assemble a computer.

CPU/CPU cooler: We all really know what a CPU is, so, we'll go more over what the different types are, and what you need to know when shopping for one. There are two main brands that make consumer grade CPUs, Intel and AMD. Each of these brands tend towards certain characteristics. Intel is known for more for higher end, performance CPUs (Duo, Pentium, i3, i5, and i7), as well as Enterprise and server grade CPUs (Xeon). While AMD caters more towards the budget market with its Athlon, FX, and Phenom lines. Long story short go with Intel, unless you have a really tight budget, and like $50-$80 dollars to spend on a CPU. AMD does offer ~$200-$300 CPUs, but they are much worse performers, as demonstrated here: http://cpuboss.com/cpus/Intel-Core-i7-4790K-vs-AMD-Phenom-II-X6-Black-1090T . The only exception to this rule I can think of is with AMD's APUs. These are CPUs with incredibly powerful on board graphics that easily exceed most solutions, such as Intel Iris, and replaces low end graphics cards in a build. This is no replacement for a high end graphics card and processor however.

Now that we have a basic idea of what each company does, we have to talk about compatibility, and how your CPU selection impacts the rest of your build component choices.

Motherboard:

RAM:

Storage:

Power Supply:

Case:

Operating System: