not sure if it is SU topic, but where to ask then? Designer create such design of some element:
is it real, and how to slice element, for example for 20px, and repeat them? I can't do this normal: if i slice this image, and repeat it then i have not a beatifull background, which everybody see - it's repeated, hot can i slice it so, that in future, when i put this as background in css it look's like it is huge image, without any repeat? how can i do it?
Creating seamless repeatable patterns can be tricky, but completely possible.
In my experience it is hard to make a repeatable pattern with a graphical patch with dimensions any less than 150px150px, so try to work with at least that.
When you select a patch that looks nice, you need to look at the edges of that patch and make the opposite sides match together. In my opinion - you can ask you designer to do this for you since it is indeed a design-task.
One tip to be able to make the edges look good next to each other is to take your selected patch in a new ps document, put it next to another patch so you see the patch as repeated, then when having one of the patches selected you can use the clone stamp tool or healing brush tool to borrow graphics from the next patch to make them meld nicely together. When you have done some cloning, remove the extra patch and duplicate the original patch next to itself to see how it looks. Repeat as necessary.
You may need some PS experience to make this work, which is why I think this is a job for a designer.
Here is agood article about creating a seamless pattern and it explains the process with some illustrations as well.
