Hi @Sara_Jeanne08,
Sorry! Looks like I gave bad advice when I suggested you could still use deblur with your data. I was mistaken about the data types that could be used as input. 
It sounds like for now q2-vsearch dereplication/OTU picking is the only method that can handle qiime1 demultiplexed data (i.e., following the first tutorial that @thermokarst linked to above). We do have an open issue here to add support for this data type with deblur, and this has been discussed previously here.
I'm sorry if my advice held you up! In any case, it sounds like we should have upcoming support for (1) dual-index reads and (2) processing qiime1 demultiplexed data in deblur, so in the future QIIME2 should be better equipped to handle data sets like yours.