And again add guides the same way as above: on 0px and 100%. Our design is now 940px wide. We will also add the center guides for border and outer guides as well. So now extend the document size with Image > Canvas Size by 20px (so it will be 10px each side) for center guides; add them the same way:0px and 100% and then again extend the size by 20px and again add same borders so you will get something like this:

At last go once again to Image > Canvas size and extend our working area to something like 1600px, so we could make big background:

Step 6 - First pixels

There aren't a lot of layers in our design (yes, there's just one)... yet. But we can end up with something like 300 layers or so. How to embrace them all? Just Grouping. It is great habit to group layers. It is easier than you think, just select layer you want to group by clicking on them in layer's window with CTRL or SHIFT (to select multiple layers) and then hit CTRL+G. You can later on change group's name by double clicking on it. You can also create empty groups without layers, just check the bottom icons in layers window.

Ok, so for now create group and name it bg, we will place all the layers there that are related to our background. First of all, let's fill our background with some color, let it be some light gray like #c9c7c2. All right, now place our paper texture (find in resources on beginning of tutorial) into the document. It's pretty small, but we will lower its opacity a lot so we can scale it up without any additional effort. Just go to Edit > Transform > Scale and stretch it till our texture will fit the document size. It will be about 343%.

Now we will gray it up a bit. Firstly we need to desaturate it completely for we don't want any color. Just go to the Image > Adjustment > Desaturation. Later on lower the opacity of that layer to about 20%.

Now we have to take care about texture boundaries. Our background will repeat only in y axis, so if someone will have a screen width bigger than 1600px it will just look awful and unprofessional. Well, we will choose the fastest path for now. Find some color that is far from center, like here: