If I say it would be the strongest backlink that any website could get, you can surely understand the real value of a wikipedia backlink. Although the wikipedia backlink is not dofollow in nature, still it can alter your keyword ranking a big way. One of the reasons why it happens can be deduced from the fact - wikipedia holds the top position in Google search for over 90% of all its queries that gets worldwide. From this data, it is quite evident that Google thinks wikipedia to be the most authoritative website on internet. And getting a backlink from there will definitely do well for your own website’s ranking. 

Getting the backlink from Wikipedia is quite easy and extremely difficult simultaneously. It’s easy because you can always create wikipedia account for free, contribute to the website and publish your own articles. At the same time wikipedia is very strongly moderated and if you found spamming you will be banned immediately and what’s more your IP will be backlisted forever. So you have to be very careful. 

As I mentioned earlier it is quite an easy job, I would only guide you to that easy route only. And I am quite sure that you can successfully get the wikipedia backlink if you follow my guide as described. 

First of all you need to create your account there and contribute (edit existing articles) in order to gain the reliability. It will take some time and you need to be patient throughout this time. Once you have edited decent number of existing articles in Wikipedia, you need to search for articles relevant to your own website. After that you can edit that article again and add your website URL as citation. After your modification you need to wait for the review period (usually 1 week to 15 days). If you can successfully pass this time period (you would), your job will be completed. And you can notice the positive result on your website ranking almost immediately.