To use a computer, you can do the following:

Turn on the computer by pressing the power button.
Wait for the operating system to load.
Use the mouse or keyboard to navigate through the user interface and open programs.
Use the programs and apppcations to perform tasks, such as creating documents, browsing the internet, or playing games.

Here is an example sentence: "To use the computer, I need to turn it on, wait for the operating system to load, and then I can use the mouse and keyboard to navigate and perform tasks."