如何更改Emacs init文件以自定义新帧的字体？

I want to know, what text do I have to input in the .emacs file so that it uses a especific font (like the clean 5x8) on the new frames, such as with the speedbar. I can modify the speedbar font size and type by using SHIFT-LeftClick but I want it to stay by default.I want to know, what text do I have to input in