The United States Copyright Office provides the following definition for copyright:
Because copyright covers both published and unpublished works, you are already a copyright holder, even if you don't have any published works. For example, for any email that you send, a paper that you write, a photograph that you take, or a video that you create, you own the copyright.
Copyright owners control:
What is the Public Domain?
Works in the public domain may be used freely without the permission of the former copyright owner. According to the U. S. Copyright Office, a work of authorship is in the public domain if it is no longer under copyright protection or if it failed to meet the requirements for copyright protection. Many U.S. federal government documents are not entitled to copyright protection under U.S. law; therefore, images within many government publications and web sites are free to use.
Which items are in the Public Domain in the U.S.?
Helpful websites about when works enter the public domain:
As you search for creative works to use in your project, you may see Creative Commons licenses attached to these works. Creative Commons is a nonprofit organization that provides free licenses that allow the owners of creative works to share their content with the public on their terms. This nonprofit organization offers a number of licenses ranging from "Some Rights Reserved" to public domain.
CC attributions vary, therefore you must read the summary of the license to understand how to use the image, texts, videos, music etc.
Try filtering your image search in Google Image Advanced Search mode in order to find images that are free for you to use.
Charts, graphs, and tables are not subject to copyright protection because they do not meet one of the key requirements for copyright protection, which is that they are not “original works of authorship” under the definitions in the Copyright Act. Facts and data aren't considered original works of authorship and therefore are generally not under copyright protection because they are regarded as “discovered” and “recorded” natural phenomena rather than “created.” Keep in mind however, that some countries do protect data and data sets, so if you are planning on taking your data abroad, be aware that the rules may not be the same as in the U.S. But, your use of data within the United States, for example, on servers in the U.S., is acceptable. Only in cases where a chart, table, or graph creatively represents more than just an expression of the underlying data, would the works be considered under copyright (e.g., a bar graph on U.S. immigration data created in the likeness of a U.S. flag). If you do need permission, refer to WPI's webpage on Requesting permission for information and a sample letter to adapt.
For examples of charts, tables and graphs that are NOT subject to copyright, as well as an example of a graph that IS subject to copyright, see the examples listed at the University of Michigan's Copyright website: http://www.lib.umich.edu/copyright/copyright-info/charts-tables-graphs
Basic Format for a reference list citation for an Electronic Image:
Author (Role of Author). (Year image was created). Title of work [Type of work], Retrieved from URL (address of website)
Example of a Reference list entry for an image:
Sipler, D. (Photographer). (2005). Nap time [Photograph]. Retrieved from https://www.flickr.com/photos/photofarmer/284159867/in/set-72157594353612286
See more image citation examples here: https://www.landmark.edu/library/citation-guides/apa-citation-style-guide#Images
A caption should include
Figure 1. Map of Nutrition, Physical Activity, and Obesity in the United States. From “Nutrition, Physical Activity and Obesity: Data, Trends and Maps. Alabama Indicator Details Percent of Adults Aged 18 Years and Older Who Are Obese,” by Centers for Disease Control and Prevention, 2015 (http://nccd.cdc.gov/NPAO_DTM/DetailedData.aspx?indicator=29&statecode=30). In the public domain.
How to write a copyright statement for an image: http://blog.apastyle.org/apastyle/2016/01/navigating-copyright-part-4.html
Read more about images and copyright: APA Style Blog: Navigating Copyright for Reproduced Images