Thanks for coming to the community! You can definitely resize an image after it's been imported into your library. Steps for doing so can be found Here. If you'd like to edit the image size before you upload it, there are online image editing programs that you can find by doing an online search.
Nate M Community Support
If you find my post helpful, and it answers your question, please mark it as an "Accepted Solution" by clicking the Accept as Solution button in the bottom right hand corner of this post.
Increase your profitability by integrating your email marketing and social media.Download this guideand learn how you can achieve great results with email marketing and social media combined!