A marketing plan and social media campaign is a pretty broad ask, and involves a lot of moving parts. It requires a base-level understanding of go-to-market strategies, and is probably an overwhelming question for mentors to answer.
In terms of social media, you can start by building your brand. This generally means posting on a regular schedule, and leveraging the relevant hashtags used by similar companies in the industry and by the folks you would be selling to. You can partner with bigger brands or influencers in the space to boost your visibility, and you can leverage paid ads on all the social media channels to increase impressions. A campaign essentially means you're posting with a similar theme across a set number of dates or for a specific reason. Ex: A sale, a contest, a giveaway, etc
I highly recommend taking a look at marketing courses on places like Coursera or CXL Institute. This will help you learn the basics so that you feel less like you're spinning your wheels. A mentor can give advice, but it's going to help you more in the long run if you teach yourself to fish first. If you get that base-level understanding, I have a hunch your questions will get more specific and be easier for mentors to jump in to help.