oh dear! How can this be? Let me help
1300+ high authority profile and bookmarking links, courtesy of
@digitalforge
https://www.blackhatworld.com/seo/a-long-list-of-high-da-do-follow-backlinks.1582679/
5000 guest posting websites, courtesy of
@Steptoe
https://www.blackhatworld.com/seo/5000-wordpress-sites-accepting-guest-posts.1539507/
dozens of link sellers in the marketplace:
https://www.blackhatworld.com/forums/seo-link-building.43/
https://www.blackhatworld.com/forums/seo-packages.206/
Unlimited guest posting opportunities you can find yourself with a bit of google research, courtesy of
@The SEO
https://www.blackhatworld.com/seo/unlimited-niche-guest-posting-and-niche-edit-opportunities-in-just-1-hour-a-day.1588897/
1000s of sites to get links from, with http://Adsy.com
And I'm pretty sure that if you search long and hard enough on the forum you will find dozens (if not 100s) of other FREE link building opportunities being shared by members constantly (this year alone I think I saw over 20-30 of them, all of the of high authority and free, like I said. You just need to search

)
I don't know what you mean by "normal backlinks", but profile backlinks are basically... well... profiles that you create on high authority sites like Disqus, Author.me, Soundcloud, etc (and insert the link into your profile). These links are almost never powerful enough to rank (because the page where you link is doesn't have authority when it's first created, but these links are free and easy to get, so many people get them. And they're also trusted by google, so you can rest assured you're not tanking your site if these are the only links you have)
handpick a bunch of quality links that come from legit sites that rank in google and get traffic from google, and point those links to your most important pages, such as:
- homepage (use branded anchors mostly if you have a brand, otherwise I don't know, maybe use a mix of generic and naked URL anchors)
- category pages (use a mix of exact match + partial match + generic anchors)
- inner pages (use a mix of exact match + partial match + generic + naked URL anchors)
Build several such quality links slowly over time (2-10 per month I think are enough if your site is new and has no backlinks yet), and increase their numbers slowly and - if after few weeks of getting these links indexed you don't see increase in traffic and rankings you can increase their number more, or start looking into tiered / pyramid link building
over time, all backlinks (at least the ones that google considers safe) will increase your DR and UR. But the links that are placed on pages with UR will probably give the biggest boost to your UR.
I don't know how DR is calculated exactly, but I assume that it takes into account all of the pages on your site that have links pointing to them, and then makes a total (or maybe average) of these links' authority, to which they (Ahrefs since DR is their thing) also add the UR of the homepage to this total / average. Again, I'm not sure exactly how Ahrefs calculates their DR but I'm pretty sure you can find the explanation yourself on their site
that'd be silly. If you want to be mr. nice guy and kiss google's hands and play by their misleading guideliness, someone else will see how weak and pathetic your SEO is and they'll build links because they don't care about google's brainwashing, and this will knock you off the SERPs to the detriment of the black hatter. And I'm pretty sure you don't want this, so go ahead and build links, but do it in a slow, safe manner to avoid tanking your site. Check this guide out on how to build links safely:
https://www.blackhatworld.com/seo/guide-how-many-links-per-day-week-or-month-should-i-build.1502403/
not gonna do this as I'm clueless about this niche (I think it falls within the ecom niche, and I never ranked ecom sites, so....)
But don't lose hope, I'm pretty sure someone else will jump in, eager to help. There's more than 1 helpful guy on this forum
you're welcome! And you have a great time on the forum, too! If you stick here for long enough you'll learn quite a few valuable things, I can guarantee you (a lot of my SEO knowledge comes from here, too)