A physical rosary isn’t necessary, but it’s nice to have one. Having the rosary rather than using your fingers frees your mind to focus on meditating on the mysteries.
When praying the rosary, you’re supposed to try and “put yourself” into the scene. For example, tonight I still need to meditate on the sorrowful mysteries. The first one, the anguish in the garden, you may imagine yourself as one of the apostles when Jesus says, “Could you not stay awake with me for one hour while I prayed?” and imagine how everyone would feel.
As for me, I just started praying the rosary for the first time on Monday, so it would be very helpful to have a booklet or maybe get to a website on your phone if you can’t memorize all the prayers/mysteries (I’m still working on “Hail, Holy Queen” myself).