Starting here.

Hello everybody! I'm new here. I was looking at your entrancesintroductions and I'm happy to knowing that there are people that who are interested in helping others. I will introduce myself, my name is Bruno, I'm 24 years old, a mechanichal electrical engineer and actually I'm working on anat a mining company. I want to improve my english skills and I will be glad to helping you learning Spanishand why not? Knowing a little about you. I'm not sure what you mean by this last bit? Perhaps "Tell me a little about you"? 

Good. Make sure you use full stops "." rather than commas "," at the end of sentences.

Starting here.

Hello everybody! I'm new here, I was looking at your entrances and I'm happy to see that there are people that are interested in helping others, I will introduce myself, My name is Bruno, I'm 24 years old, a mechanichal electrical engineer, actually I'm working for a mining company, I want to improve my english skills , and I will be happy to help you with spanish, and also getting to know a little about you.

Starting here.

Hello everybody! I'm new here. I was looking at your entrances and I'm happy knowing that there are people that are interested helping others. I will introduce myself - My name is Bruno, I'm 24 years old, a mechanichal electrical engineer. Actually, I'm working on an mining company. I want to improve my English skills, and I will be glad helping you learn Spanish, and why not? I will get to know a little about you.

[Good start.  Completely separate ideas should have separate sentences]

*I would also like to learn a little about you.