The counterpart to mongodump is mongorestore (and the counterpart to mongoimport is mongoexport) — the major difference is in the format of the files created and understood by the tools (dump and restore read and write BSON files; export and import deal with text file formats: JSON, CSV, TSV.
If you’ve already run mongodump, you should have a directory named dump, with a subdirectory for each database that was dumped, and a file in those directories for each collection. You can then restore this with a command like:
mongorestore -h host.com:port -d dbname_test -u username -p password dump/dbname/
Assuming that you want to put the contents of the database dbname into a new database called dbname_test.