Photoshop or any other software won't create a good logo for you. It's just a tool.
To create a good logo, you need to know what makes a good logo.
And that's just touching the very basics. A fundamental understanding of branding, graphic design, visual grammar, and composition would help a great deal. There are plenty of books that cover these topics. Try your favourite book store for some titles.
It's good practice to draw out variations of your logo with a simple pencil/pen and paper first. Do some iterations. It's only after these that a tool like Photoshop, or much better as Ralph suggested, a vector program is of use to you.
Sites to get you started: