how to apply a texture with the size suitable for solid to make

[SUSANNA]

I finally managed to use the UV map. I carry on photoshop the unwrap uvw, that is the contour of the face of the wall that I want to map.
I fill the contour with my texture and then re amount on 3dstudio.
However, when I make, the texture is always or well defined but too large (just stones for 20 meters of wall!!) or very blurred (thanks to my attempt to reduce the size of the texture on photoshop).
what is the right process to measure the texture well?
I tried to import the wall from autocad resize with the dimensional parameters of 3d studio, but if I do so then I can not manage the perspective view of the wall, it turns out planted, neither does the zoom nor the orbit...
What's wrong?

 

[lattu]

but why do you persist in using unwrap?
uvw map can handle the texture as you wish.
after applying the texture to the rectangular face, and disabling the real-world map size, click on manipulate and drag the tops as you want

 

[SUSANNA]

Yes, in the end I solved so... I was impunced because I was following a tutorial and detested when, while following the directions step by step, I see you out a totally different thing:
Thanks for the advice!