There are many systems for writing in roomaji. We use the Hepburn system, modified to match the kana characters as closely and possible. When you learn Japanese in this way, it is easier to move on to write in kana and kanji.
Roomaji text is written in the Latin alphabet (e.g. neko, cat). If you are using a Japanese language setting, select Half-width Alphanumeric.
The roomaji Japanese you learn with WordDive has spaces between words to help you learn where each word begins and ends.
Normally, the Japanese language does not have these spaces, so if you prefer not to use them, that is accepted as well. For example, the expression below can be "koukishin ga tsuyoi" or "koukishingatsuyoi".