link errors – sending to bad URL

Hi, I uploaded wordpress onto my site and applied a theme to it and customized it a bit. After checking some of the links I found that some don’t work. for example the links for “about” “log in” work but things like the “uncategorized” category sends me to an error page and in the error page I noticed that there is a slash missing…

My sites’ URL is https://www.fiftyfootkiller.com and when clicking on the “uncategorized” link on the left sidebar it sends me to the following URL “www.fiftyfootkiller.comcategory”. I noticed the “/” is missing but fixing it goes beyond my very basic knowledge of php. Any ideas on what might be causing this?

Thanks for your time.