You can get the matching segments from Gedmatch, MyHeritage, 23andme and/or Family Tree DNA. In future it's anticipated that other vendors will provide this information.
Gedmatch, MyHeritage and Family Tree DNA accept transfer uploads of autosomal DNA test results. If you haven't already, consider uploading your DNA to these sites in order to find more matches.
Gedmatch (http://www.gedmatch.com) uses kit numbers. If you know the kit number of the match, you can go straight to the 'One-to-one' compare tool. Enter your kit number in the 'Kit Number 1' box and the other kit number in the 'Kit Number 2' box, and click the submit button.
You can also access this tool via the 'One to many matches' tool by clicking on the 'A' in the row for a match:
The results look like the picture below. You can copy and paste the table data (it doesn't matter if you include the header or other data as well) straight into the 'Paint a new match' form.
MyHeritage matches are available at https://www.myheritage.com/dna/matches/. The company sells its own DNA tests, and you can also upload your raw DNA to their site and they will provide matches from their database once your file has been processed. You have two options for accessing segment data:
Option 1: Click 'Review DNA match' on the match you're interested in so that you can access the segment data.
On the detail page, scroll down to the chromosome browser at the bottom of the page (please note - you might need to be on a desktop device in order to see this section).
If you click 'Advanced Options' at the top right of this table, a link to 'Download shared DNA info' appears. If you click this link, a file will download containing the match segments. You can paste the contents of this file (either comma delimited as it comes, or after opening in a spreadsheet programme such as Excel) into the 'Paint a new match' form on the DNA Painter site.
Option 2: Go to the Chromosome Browser and select yourself and your match. At the bottom of the page you'll see a section called 'Shared segments info' with a table of data that you can paste into DNA Painter.
23andme matches are under Tools > DNA Relatives. You can't transfer your DNA to 23andme; you have to have done one of their tests. To get the segment data, you have to either click 'Download aggregate data' for a spreadsheet of all segments, or go to the DNA Comparison view at https://you.23andme.com/tools/relatives/dna/. After you click a match to compare, the segment data will appear in a table at the bottom of the page, which you can paste into the 'Paint a new match' tool in DNA Painter.
You can also import segments from 23andme that correspond with ethnicity estimates. To do this, visit this page and click 'Download Raw Data'. These segments can then be imported via the 'import ethnicity' tool.
Family Tree DNA
If you've tested with Family Tree DNA or completed an autosomal transfer, you can view your Family Finder Matches at https://www.familytreedna.com/my/familyfinder/. Tick the checkbox to the left of the match you're interested in, and click the 'Chromosome Browser' button.
This will bring up the Family Tree DNA Chromosome Browser:
If you click 'Compare', you'll be taken to a page showing the chromosomes and a graphical representation of the DNA you share. If you click 'Detailed Segment Data', above the chromosomes, you'll see a table.
You can copy and paste the segment directly into the DNA Painter 'Paint a new match' form, or if you prefer, you can click 'Download segments' for a CSV file, which you can then copy and paste into the same form.
It's worth noting that Family Tree DNA include even very small segments in their data. Many geneaologists disregard these small (less than 7cM) segments as they might be coincidences rather than genuine matches. If you're not sure, you can keep the small matches and delete them from your profile later. The nice thing about painting them is that any overlapping or proximity to other matches will be obvious.
You can copy and paste this data directly into the 'Paint a new match' form, or if you prefer, you can download the Excel file and paste in columns 3-7 (starting with Chromosome and ending with SNPs).Next: Assigning segments