If you just want to apply a specific font to your entire page you just need to specify your font in the body.
font:[weight], [style], [size]/[line height] ;
Since you are using a CMS, you need to find whatever file includes your head tag and include a link to the stylesheet OR just take that stylesheet and add the contents into your css file.
For example, if you want to use the font ‘OSWALD’ just get the stylsheet and add its contents into your css file.
src: local('Oswald Regular'), local('Oswald-Regular'),
In the body element just add the following:
font:normal normal 16px/1 'Oswald';
Does that help any?