Hi rarmada, you generally would use the Construct > Offset > Shell command to thicken a surface into a solid.

But that will only basically work when the surface you are thickening is one completely smooth piece. When you try to thicken something that has sharp corners and little side pieces hanging off it's a much, much more complex problem.

Check out here for a recent discussion with some links to previous discussions on this topic:
http://moi3d.com/forum/index.php?webtag=MOI&msg=5633.3

Something like what you have there has a lot of things that make it complicated to thicken - pieces that are close to being smooth to one another but actually at a shallow angle - long thin pokey parts, .... I'm not sure that there would be much chance of automatically thickening something of this level of complexity. You may need to work on it on a more manual level, that would be by breaking it apart into individual surfaces and then using the Offset command to generate offsets, and then work on trimming or doing some additional modeling to build up connecting parts between the offsets.

- Michael