When you have found an OER that you'd like to adapt, assess the following:
Subject librarians can contribute to the planning process and help you adapt existing resources to your context.
When editing an existing OER, consider how your audience and learning objectives differ from those of the original work. Your goal should be to bring that work into alignment with your specific context.
Depending on the format of the original work, you may be able to do your editing in the document itself - for example, a Word or OpenOffice document can easily be edited using those programs or a web-based alternative like Google Docs. There are also specific authoring tools like Open Author and PressBooks which can be used for this purpose.
For more information, check out the resource "Modifying an Open Textbook: What You Need to Know".
You should release your edited work under a free license that is consistent with the licensing requirements of the original. For example, if the original work used a Share Alike CC license, you must release your work under a compatible license in order to comply with those terms. You should also consider making your work available in multiple formats, if possible.
Edited works can be shared directly with students, either in the classroom setting or using a course website. You can also post your work to one of the OER repositories listed on the page on Finding OERs.