For WordPress Website optimization you should take a look at: https://codex.wordpress.org/WordPress_Optimization
I took a look at your pagespeed report and the main thing there are the images you are using. There are many plugins that can optimize them for you. I like this one in particular: https://wordpress.org/plugins/imsanity/
As per the server cache, you can either try the popular cache plugins or ask a sysadmin to optimize these options for you on the server level.
In my case. Using Apache 2.4 I have this configuration in my pre_virtualhost_global.conf:
# Cache Control Settings for one hour cache
<FilesMatch ".(ico|pdf|flv|jpg|jpeg|png|gif|js|css|swf)$">
Header set Cache-Control "max-age=3600, public"
</FilesMatch>
<FilesMatch ".(xml|txt)$">
Header set Cache-Control "max-age=3600, public, must-revalidate"
</FilesMatch>
<FilesMatch ".(html|htm)$">
Header set Cache-Control "max-age=3600, must-revalidate"
</FilesMatch>
# Mod Deflate performs data compression
<IfModule mod_deflate.c>
<FilesMatch ".(js|css|html|php|xml|jpg|png|gif)$">
SetOutputFilter DEFLATE
BrowserMatch ^Mozilla/4 gzip-only-text/html
BrowserMatch ^Mozilla/4.0[678] no-gzip
BrowserMatch bMSIE no-gzip
</FilesMatch>
</IfModule>
Pagespeed also offer instructions on the other factors. You should follow them.