You have MySQL database. And want to move either all, or some of the data into MongoDB. There is no direct way to do it, as such, It can be done in two steps. (If you are here because you have a csv file instead (or directly) move on to Step 2.)
Export all of your MySQL data as a CSV file.
select columns INTO OUTFILE '/path/to/csv' FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"' LINES TERMINATED BY '\n' from table [where clause]
Import the CSV into MongoDB.
Assuming you have MongoDB running (on local, defaults) run the following command
mongoimport -d dbname -c collname -type csv -f fields-sep-by-coma --drop /path/to/csv
if your csv file has a header row add --headerline.
p.s.: for more options on mongoimport look here
More tips on mongodb, coming