making textures/materials fit without stretching them

match numbers here with the numbers on the picture

1. i find a texture to assign a wall or floor

2. i assign it, and it repeats itself.

i can't click "fit", because that just stretches it out

http://img127.exs.cx/img127/3442/textureproblem1ci.jpg

See that 512x512 by #1? Make the brush face you want it attached
to one quarter of that size (128x128). Then, hit fit. The
texture size SHOULD be at .25, that's what they're made for.

then what textures do i use for walls and floors?

Most walls and textures in HL2 ARE supposed to be at .25 or .50 scale, they are meant to repeat.
The repetition just usually isn't so obvious in-game, when you have
lighting and props. Using decals, overlays, and props effectively can
also divert the player's attention so that repetition won't be noticed.
Look at a few HL2 screenshots sometime and you can see there is a lot
of repeating, but the designer used clever placement of elements and
lighting to mask that blatant tiling.

Remeber, the normal height of a wall is 128 units tall. try and
keep all your brush work for walls and floors a multible of 16, that
will ensure that the textures fit and look right.

how do i make a brush a specific width and height?

as you drag the brush creation tool you will see numbers along the top
and bottom, that is it's size in units. There is also a space
down in the lower right that shows the x y z dimentions of your brush.

oh i thought there might be a way to type it in

its really easy just to drag it, press the "]" to make your grid larger
and make sure that you unit's snap to the grid (press shift+w to toggle)