I have pasted in the sources section below a link to the Guide to Literary Terms, in which each of these devices is defined. I'll give you a couple examples of each and let you find the rest of them in the poem.
Personification occurs when the author gives human characteristics to an inanimate object or animal. Look at how Owen describes the guns and see if you can find personification in them.
Similes and metaphors are comparisons; simile uses the word "like" or "as," and a metaphor does not. One simile in the poem is in the line "His hanging face, like a devil's sick of sin." An example of a metaphor is the expression "blood-shod." The soldiers have lost their boots, and their feet are bloody instead.
Irony occurs in the whole poem, especially with the title and the final lines, which can be translated as "It is good and fitting to die in the service of one's country."
Imagery is mental pictures that the poem evokes for the reader. I won't give you any examples of imagery because that should be something you can "imagine" for yourself. Hint: the poem is full of images of war and pain.
it is hard to figure out the literary terms while you are not a native speaker of English language , and this is my problem , too
I am gonna give you some examples those are quoted from other websites . they may help
Metaphor and Simile
Dim, through the misty panes and thick green light,
As under a green sea, I saw him drowning.
Simile: Comparison of the mist of green gas to a sea
Metaphor: Comparison of the gas victim to a victim of drowning
SimileKnock-kneed, coughing like hags, we cursed through sludge
Comparison of a soldier's coughing to the coughing of a witch
His hanging face, like a devil's sick of sin
Comparison of a soldier's face to a devil's face