Ok this is a short tutorial about making the texture sheet.
First open a picture editing program of your choice they all look very similar, here I used GIMP (you can download it free, just google it)
Click on File>New (fig_1) then a small window open where you can put in the size of the new file. Here you have to type in 256 and 256 because we want to do a texture for a repeatable building. (fig_2)
When we click on OK we see our new file.
Now we have to open the file with the picture for the texture. (fig_3) On this picture you have to select a part, for example the roof. And the copy this part and paste it as new image. (fig_4)
Now we can scale the roof to the right size we can easily put in 256 as high and it fits perfectly into the texture file. (fig_5)
To put it in the texture file copy it again and insert it as new layer. (fig_6)
These steps you have to do with every part of the texture.
If you have any questions please ask.
I hope this helps.
Kind Regards,
Joey