Hi Justine,
Thank you very much for comments foe for the longitudinal and paired sample comparisons with q2-longitudinal and it is helpful.
I am trying to run songbird but I have some inquiries in the bellow commands from the first step
What does mean "data/redsea/redsea.biom" or from where this file comes.
The redsea.biom file there is an example "feature table" (stored in the BIOM format), containing abundance information for features (e.g. ASVs, OTUs) and samples.
Some QIIME 2 plugins will generate feature tables—for example, DADA2 or Deblur, if you run them through QIIME 2 (see the Moving Pictures tutorial for examples of this). In this case, these feature tables are saved as QZA files ("QIIME 2 artifacts")—these contain both the "table data" (e.g. a BIOM table file) and other internal information (for example, provenance data -- this enables us to look at a QZA file and see when it was created, how it was created, etc.). If you are interested, the QIIME 2 overview tutorial has a lot more information on QZAs.
However, often people might already have a BIOM table created from outside of QIIME 2 that they would like to use within QIIME 2. In this case, the command you posted above (qiime tools import ...) can be used to import a BIOM table file into QIIME 2, so that it can be used by a QIIME 2 plugin (like Songbird).
If you already have a feature table stored as a QZA file, and you want to run Songbird, you can just skip to the next command in the Songbird QIIME 2 tutorial (qiime songbird multinomial ...)