Change text and add a link in thank you page

-- url of the page with the problem -- : voetbalgek.info/
-- HikaShop version -- : 2.3.4 business
-- Joomla version -- : 3.3.6
-- PHP version -- : 5.3.29
-- Browser(s) name and version -- : all
-- Error-message(debug-mod must be tuned on) -- : not relevant

After finally struggling for a while with sending customers after checkout to a thank you page I've made it, BUT
I have found the dutch text string in language file nl-NL.com_hikashop.ini - but how and where is it possible to set a link:

Back to homepage and/or continue shopping ?

With other words, where can i find and edit the thank you page?

happy easter to all of you

I am sorry but even I followed your instructions I was not able to find where I can change the html code / text and link on the page?