Before I start this comment, "R" stands for Range.
Don't listen to Fluxeon's pessimism, it'll hurt you. Anyways, when I started this game, I just put whatever the hell things with high damage. (Didn't get me anywhere, but it was fun. Nonetheless, don't do it.)
The game is very easy to learn. Just learn these basics. Numbers aren't important (having a lot of weapons), it's how they work together. Less is more. As long as the weapons you're using covers all the ranges, you're good. (But make sure the used items attains the needed relevance for the concept of your mech)
So there are three build types in this game:
1. Physical (Deals as much damage as possible)
2. Heat (Stops people from doing their turns)
3. Energy - If you fought people with the blue stuff and deals like 140 damage, and as a newbie, it's quite scary. The mechanic behind this is simple. You see, the main goal of an energy mech is to drain your energy and deal massive damage. How do they get the "additional damage"? So let's say "Lightning Axe" does -50 energy damage and has a base of 60 damage. Enemy A hit you with the Axe and you have 0 damage. Missing energy damage converts into raw damage. So Enemy A does 50+60=110 damage.
As you can see from Namy's post, that's a good example of "Covering all your range".
The black thing you see on the bottom left is a "Firewall". Its R is R1-3. Anything that can reach R1 with a knockback is staple in anything that doesn't use rocket launchers (in other words, mechs that don't use bullets and rockets. That said however, I've seen mechs that uses ammo that are combined with "a weapon that can reach R1 and has knockback). Best choices are "Saurus Rifle" and "Firewall".
As pointed earlier, copying of mechs are bad because you still don't know how they work (assuming you already have "The Meta" items at this early). But trust me, simple observation and at least a week of experience can help you get the builds easily. As I've said earlier, this is an easy-to-learn strategy game.
Though if you still need more tips, you can always ask us SM Community (Except Fluxeon)!