I have been doing SEO for three years now. But, it seems many of the SEO jobs i'm applying for, currently, require ppc. Does anyone have any ideas how I can gain some experience? At my current job, i'v created some negative keywords, and Ad groups. But, have not run any campaigns.
As you are already working in SEO, you must have good exposure of keyword research and landing page optimization. As suggested by other, first create dummy campaign by reviewing Google adword guide suggested by Minnapple.
If you are having website, run a test campaign (you can easily find coupon from $50 to $200) for running your first campaign.
Keep watching your campaign and do the require changes. Keep asking at Google Adwords community https://www.en.adwords-community.com/, one of the best place to find answers of your question.