Interested in starting to work out but don't know where to begin. Any advice?

Find a friend that goes to the gym. If not, you can hire a trainer to teach the basics.
Proper form >> weight.
You are underweight. You need to eat more.
After getting the basics done, you can find a beginners routine in the internet. You can do something like full body 3x a week, an Upper Lower split 4x a week, Push Pull Legs 6x a week, starting strength to give you the strength for doing compound movements, bench press, squats, deadlifts, overhead press.
Consistency is key, don't push yourself hard first. Try to make atleast going to the gym a habit, then go you go push your limits.
If you have any questions just ask

 

I do Mixed martial arts twice a week and everything was/is being shown to me, I would highly recommend doing something like this makes you feel so much better.

 

First things first, find a gym you feel comfortable out, a lot of gyms offer a trial or one day fee. After that, I'd recommend getting on a program that suits your needs. Mass Strength training, body build training, and cutting. With your build I'd assume you'd want to body build or strength build. I personally enjoy body building programs.

If you decide to use body building, try the BLAST Evolution by Ryan Hughes. It's a 90 day workout that does the charm.

 

My Advice is to look at youtube. A lot of free shit, free plans, free everything there.

Make sure you eat a fuck ton of protein, 1g/lb.

The only 1 supplement you need is creatine. Take protein if cant eat that much food in a day. It is very convenient and cheaper.

You should eat at a caloric surplus. Since you're just starting off I'd dirty bulk. Easy since it looks like its hard for you to put on weight.

Seriously can't stress it enough. Youtube is the way to learn.

 

dont fret over all the vids and postse about working out. just focus on getting into the habit! and then slowly trying new excercises