Can't create 3D mesh

Hi everyone, 

 

I'm a new user, from Spain and I've worked the student-version for 1 month. I hope we can help together.

 

I have created a mesh as the tutorials says. Then, A 2D mesh it's created. Due to the complexity of the geometry I have some error_elements. I solve them but later, I can see that it's not a enclosed volume. I've tried to solve it with different methods that I've read in the tutorials but I can't get it. That's why I've come here. 

 

1) Could anyone help me? I don't know how to solve those red and yellow lines. 

 

2) I suppose than once again I've solved them I could mesh in 3D?

 

Pd: I add an image.

 

Thanks very much in advance. Hopelessly, I'm findind some help jajaj. 

 

<?xml version="1.0" encoding="UTF-8"?>