How to make simple mesh
1, Open a new image, 4x4px, Transparent
2, Zoom in on this new canvas, 1600%, till it wont become any bigger
3, Select the Pencil Tool and change the brush to "Hard Round 1 Pixel"
4, Choose your colour for the mesh i.e. if red (#FF0000) I will choose a darker shade namely (#D00000)
5, Colour in the canvas with the Pencil Tool as shown in the picture below.
6, Now go to Edit > Define Pattern... and click OK
7, Now the pattern has been loaded into Photoshop so you need to apply it to your kit. Double click the layer you want to apply it to on the Layers tab, tick Pattern overlay and find your pattern.
8, Adding a few more effects and you should now have your mesh looking a bit like this
You can also try making your own mesh patterns, the pattern above isn't the one I use, on my mesh I have added some opaque brush strokes and very low lighter and darker layers.
Happy mesh making!