See discussion for a tutorial on the passive voice and how to use it in Latin, including external links which explain future, imperfect, and present indicative passive verb forms.

I consider commercial textbooks to be inadequate, so I do not believe that this article can wait.

Here are the conjugations for the imperfect passive tenses. The basic rules for going to passive are:

In the first person, add -r if the active ending is a vowel, otherwise change the final constant to an -r. Examples:

paro (I prepare) -> paror (I am being prepared)
aperiebam (I was opening) -> aperiebar (I was being opened)
defendemus (we will defend) -> defendemur (we will be defended)
tenebimus (we will hold) -> tenebimur (we will be held)

In the third person, add -ur. Examples:

parat (he prepares) -> paratur (he is being prepared)
aperiebat (he was opening) -> aperiebatur (he was being opened)
defendent (they will defend) -> defendentur (they will be defended)
tenebunt (they will hold) -> tenebuntur (they will be held)

In the second person, things get more complicated. For the plural, replace "tis" with "mini". Note the exception in "ferre", where "fertis" becomes "ferimini". In the word "ferre", the "rm" letter combination consistently gets separated (ferimus instead of fermus, ferimur instead of fermur and ferimini instead of fermini). For the singular present, take out the active ending, add the thematic vowel (a from -are, e from -ere, i from -ire and nothing from -re, as in ferre) of the verb's infinitive ending and add -ris. Examples:

paras (you prepare) -> pararis (you are being prepared)
tenes (you are holding) -> teneris (you are being held)
defendis (you are defending) -> defenderis (you are being defended)
audis (you are listening) -> audiris (you are being listened to)
defendetis (you will defend) -> defendemini (you are being defended)
amabis (you will love) -> amaberis (you will be loved)

Note the -eris ending in the future passive. The future active bo, bis, bit, bimus, bitis, bunt looks like the third conjugation so the passive bor, beris, bitur, bimur, bimini, buntur looks like the third conjugation. The imperfect passive is bar, baris, batur, bamur, bamini, bantur.