Once you’ve created a text frame using the type tool (t) and inserted text into the frame you can begin to define the formatting. At first, just set the formatting for the first paragraph of your text.
The first feature to note is the Character Formatting Controls. This panel runs along the top of your screen and will appear by default when you open InDesign (or go to Window > Control to open).
From here you can set the Font, Font Weight (Regular, Bold, Italic etc), sizing, leading (space between lines of text), and text Color, as well as more advanced settings like Drop Cap number of lines, indents, kerning (the space between two individual characters) and tracking (adjusts the space between characters uniformly over a group of letters).
You can switch between the Character Formatting Controls and the Paragraph Formatting Controls, which sits in the same panel, by clicking the icon to the left of the panel. Here you can alter the arrangement of the text, setting the alignment of paragraphs, and again it offers the option to set indents, Drop Caps etc.
Once you are happy with the formatting of your first section of text, you can tell InDesign to remember these settings by creating a style.
Sit your type cursor within the paragraph of text you have formatted, then go to Window > styles > Paragraph styles. From the drop-down menu (click on the three bars at the top-right of the panel) select new Paragraph style. Name the Style appropriately (e.g. Body Text or First Paragraph of Chapter), then click Ok.
To apply the style to other sections of text in your document, either insert the type cursor into the relevant paragraph, or highlight the bulk of text you want to apply the style to, and click on the style name in the Paragraph styles panel.
You can also set styles for individual Characters. For example, you might want to create an occasional colored, Bold, All Caps WORD within your text. You can set this as a Character style in the same way you would a Paragraph Style. Go to Window > styles > Character styles and create a New Style, as above. Then to apply the style, highlight relevant letters and click on the style name in the panel.