will using a slide ruin your guitar? im a beginner and have never used one before.
Why do you think it would?
No. The only thing it can ruin is your strings and no, it's not going to ruin your strings.
If you purchased one of those heavy brass slides, and say, threw it across the room at your guitar, you may successfully dent your guitar. It would still be entirely playable though, so not really ruined. If you use the slide like it is intended, what gives you the idea that there would be any detrimental effect at all?