We will export the pdf file after finishing the typesetting in indesign. There are two kinds of pdf files, for printing and web.
For web: the size of pdf file will not very large. So we just ensure the text and the picture can be look clearly. 
For printing: then it requires a relatively high accuracy of the source file. But there will be so many problem to somebody in seting up the expert of pdf. Now I wil try to explain it in detail and hope it will help you.

First, there are two kinds of method to open the exporting pdf menu: File > Export or Ctrl + E 

Then it will appear a dialog box

Adobe PDF preset

In general, every company has its own standard, so we can save the configuration when we set up it. When we use it next time, we only need to call it.

The effect of the parameters:

indesign general panel settings

There are some point need to attention in indesign general panel:

pages: 
Spread：
Others setting generally for pdf

pdf export panel:compression set

Set up the rates of picture compression

pdf export panel: Marks and bleeds set

Marks and bleeds is a more importment parameter because of the bleed. We choose all options in Marks.In the choose of Bleed and Slug, we choose the Use Document Bleed Settings if the document has set the bleed. If not, we need to set the number: 3mm.

pdf export panel: output set
In order to keep the color as the source, we choose  "No Color Conversion"

pdf export panel: advanced set

"Subset fonts when percent of characters used is less than": this must be 100% so that all fonts used in Indesign can be embedded in pdf. The fonts will not lose in the next step such as printing.

that's all about pdf export in Indesign, I hope it will be useful to you.