Prepositions of time
First, try this online quiz. Then, try this exercise. After that, try this one. Next, try this exercise on how to correctly use "since" and "for". Finally, have a look at this site which explains present tense and present progressive tense.
Time Order
When we want to tell someone how to do something, we write the steps involved.
We also have to do this when we are describing something that has happened (or will happen).
We call this "time order".
When we describe objects in a space they are located, we call this "space order".