There are multiple ways to sell 5000 copies of your book online these include
Getting more reviews
Having more active video content with a link to your book sales page
Using the right hashtags
Using facebook and social media marketing consistently
Research the book your going to write, look at what audiences are searching for and write the title accordingly.
Ask a lot of questions on question and answer sites and forums.
Pay attention to popular tending books in your niche why were they bestsellers, what were their strengths
Get people online to refer your book
Add your book to a referral scheme
Have a blog solely about your book and build engagement
Develop your authority on the subject your going to write a book about. This means your sOcial media, business site, and anything you publish linked to this niche will show how much you excel in this arena. You are delivering yourself as a brand authority in this field, and you want the search engine, and the algorithms to give you notoriety for this skill. Have a facebook group or join other facebook groups, put time aside to be active online commentating on others posts, tweeting your insights, your knowledge, and your recommendations.Post on book sites, instagram pages, tumbler, bookish online, and online book clubs. Leave memorable insights and inspired quotes if tempted so you can be remembered.
Support the team
Comment on the work of other writers, inspire , encourage, build a network and actively support them. Retweeting, sharing, liking, subscribing, and recommending their work, so the love can be recycled. Sites like Twitter/facebook/linkedin/tumblr/instagram/ are great for this.
Ask bookshops to promote your book, spread the word with quirky bookmarks, offer to do readings, offer to hold workshops and creative writing classes in schools and libraries, anything to engage your audience and have them put the word out about your book.
Set up a sales commission programme for young people who are interested in sales, they can spread the word about your book, sell copies for you and get a commission
Ask influencers to share a copy of your book on their page, tag and mention.
Put out online press releases, and contact media yourself for interviews, ask to get on podcasts and youtube channels.
Have a can do attitude, watch sales seminars, and engage with your audience through your blog or website.