If you want to get started as a lyricist then I think you should really study the subject to propel your writing forward because there are quite a few technical things to consider when trying the words to popular songs.
The best book I’ve found on the subject is Writing Better Lyrics by Pat Pattison.
Pattison has also written some other books which delve deeply into specific songwriting subjects (Writing Better Lyrics is more of an overview) such as Songwriting: Essential Guide to Rhyming and Songwriting: Essential Guide to Lyric Form and Structure which are also very highly recommended.
If you are interested in writing melodies for your lyrics as well as the words (rather than working with a musical composer) then you really need to realize that’s a whole subject of its own (and in my opinion even more important for the success of a song than the lyrics.) Some suggestions to get started are Melody in Songwriting and The Songwriter’s Workshop: Melody.