If run-on and comma splice errors are still a struggle for you, here are some links that may help. Each site offers slightly different approaches, so check them out to see which is most helpful for you.

Many universities and colleges have grammar help online. I have included one, but you could easily search for others.

http://writing.umn.edu/sws/quickhelp/grammar/runons.htmlLinks to an external site.

OWL-Online Writing Lab is a great source for grammar and basic writing information. I have selected the link to run-on sentences, but the whole site is helpful.

https://owl.english.purdue.edu/owl/resource/598/02/Links to an external site.

https://owl.purdue.edu/owl_exercises/sentence_structure/sentence_structure/run_ons_comma_splices_and_fused_sentences.htmlLinks to an external site.

Grammar Girl quick and dirty tips is another site I like for general grammar and basic writing tips. It often offers additional pages and videos on each topic. It can be a bit busy to navigate. I have included the run-on sentence url.

http://www.quickanddirtytips.com/education/grammar/what-are-run-on-sentencesLinks to an external site.

There is absolutely no shame in taking it down a level so that you can relearn a basic grammar rule. So, here's a link to a junior/high school site.

http://www.myenglishteacher.net/runonsentences.html