There are many editions of these poems due to their incredible popularity all over Europe; take a look at the many results at Internet Archive and Hathi Trust. The reprint of the 1773 edition at Sacred Texts is definitely the best place to start, and then you can explore further if you are intrigued by this wild episode in the history of Celtic literature; the table of contents below is linked to the Sacred Texts edition.
Preface
A Dissertation Concerning the Era of Ossian
Dissertation Concerning the Poems of Ossian
A Critical Dissertation on the Poems of Ossian by Hugh Blair
Funeral Song by Regner Lodbrog, translated by Olaus Wormius
THE POEMS OF OSSIAN
The Songs of Selma
Fingal: An Ancient Epic Poem
Book I
Book II
Book III
Book IV
Book V
Book VI
Lathmon
Fingal: An Ancient Epic Poem
Book I
Book II
Book III
Book IV
Book V
Book VI
Lathmon