How do I import project from ms project to Primavera p6?

Very well said till now and it’s enough to do the job, but still you want something more you can find that on youtube

Go to files-import- Microsoft project- MPX - then browse for the MS Project backup MPX file..

Use Files Import function.
Tick mark MS Project as source file.

First, you need to have your designated file in MPX or XML format when exporting from MS Project; Click on file import, select "Microsoft Project" and the format from the drop menu, then locate the file to start importing; follow the import wizard steps until the program starts importing.
If you have MPP file, which is outdated after MS Project2007, you need to just import it in MS Project then export using XML which P6 can read.

File- Import-Ms - Choose your version -and then the fields