Update Worldpay and add SSL security to website

I have recently taken over running a promo staff/recruitment website. In a nutshell, it advertises jobs (typically promo & field marketing roles) which are posted by agencies and companies around the UK (they pay a fee to do so). Members then apply for those jobs, with alerts being sent to the advertiser.

I need a developer familiar with ASP.net and Worldpay to help make the following updates/changes to the site:

- It currently has an outdated Worldpay 'Bureau' account belonging to the previous business owners that needs to be updated to my new Worldpay account. Note that the new account has a DIFFERENT configuration to the old, outdated account - is it NOT a simple case of updating new API keys.

- The site is not secure and requires installation of SSL security (eg Let's Encrypt).

- Make small text changes to the contact page.

Most importantly, this is a new business to me and I have NO prior knowledge of how the site was developed. I have literally bought the site in the last week or so. When submitting your proposal it is vital that you bear this in mind - that you will be working with someone who has no previous working knowledge of the site. I am just trying to get it up and running properly.

So I am looking for someone very experienced in troubleshooting independently, and someone who is very experienced in how Worldpay works. I'd greatly appreciate if you could elaborate on these when making your proposal.

I am seeking to start an ongoing relationship with a developer, so with any luck this will be the start of this - I have many updates and changes planned for the website.

Once we've made contact I can provide you with the URL of the company so that you are better able to give me an idea on timescale and costs. Many thanks.