how do you mold 2 objs together w/ out meargeing polymeash, like the weld point tool? but form one cube toanother, the blue lines in this pic, are they from that?

A blue line means an edge which is only connected to 1 poly. If you've got another blue line, IN THE SAME MESH, like this:
__________
[__________]

__________
[__________]

Select both edges, and press the right mouse button on, or close to them.

Weld:
__________
[__________]
[__________]

Bridge:

__________
[__________]
[__________]
[__________]

Hope this helped somehow..

the dark blue, not the light blue, i know that, lets say u make 2 cubes and put them ontop of each other about 1 unit of space inbetween, adn delete the top of the bottom cube and the bottom of the top cube. how would i weld the points form cube to cube?

to make these points connect

MandeRek wrote: Weld:
__________
[__________]
[__________]

Bridge:

__________
[__________]
[__________]
[__________]

Hope this helped somehow..

Or bring them closer, and merge, with whatever amount of tolerance you need for the meshes to combine.
But you mentioned not wanting to merge them.

The dark blue lines means those edges are hard. You use that when you want the edge to be noticed to make a 'crease' sort of thing the model. It's pretty useful if you want your model to look not so round and smooth.

Have a look at THIS link, it'll help you understand what hard edges are, how to use them and how they affect the geometry.
For welding points have a look HERE.